Relative to bodyweight, the male tuberous bushcricket has the largest testicles of any animal on Earth:

The sperm-producing organs account for 14 percent of the body mass of males of this bushcricket species. The previous record holder's testicles—belonging to the fruit fly Drosophila bifurca—tipped the scales at about 11 percent of its body mass.

"I was amazed by the size of the testes—they seemed to take up the entire abdomen," said study leader Karim Vahed, a behavioral ecologist at the University of Derby in the U.K.